The invention relates to an impact protection element for a vehicle.
Side sills are known as impact protection elements for vehicles.
Their crash capability is determined by crash tests. Euro NCAP (European New Car Assessment Programme) is an organization which carries out crash tests on new types of car and then determines the safety of the vehicles. Pole side impact is part of the Euro NCAP crash test. In this case, for example, the impact of the side of the vehicle with a tree or post is simulated by the vehicle being catapulted at 29 km/h against a stable pole. This crash test is a standard requirement in the U.S. The following is defined as a pole impact in the FMVSS214 loading case: the vehicle moves on a slide laterally in the direction of the pole (rigid composed of steel); the slide is braked and the vehicle slips further against the pole; the impact speed of the vehicle against the pole is 32 km/h. Possible injuries to the vehicle occupant in the head, upper body and lower body region following the crash are detected with aid of a dummy.
Up to now, the floor assembly of the vehicle and of the side sills has been constructed in metal. There is a clear separation of components and function between the side sill and floor assembly. Energy is absorbed by means of buckling in the seat cross member and in the floor assembly, and also by means of bending in the side sill. The load is distributed extensively, and the resulting bending load of the side sill opposes the intrusion.
It is the object of the invention to further reduce the intrusion and to provide a lighter weight side sill having increased rigidity.
According to the invention, this object is achieved by an impact protection element for a vehicle having a side sill composed of fiber-reinforced plastic, where the side sill is formed as a hollow profile, an outer wall element which forms an impact surface, an inner wall element which lies opposite the outer wall element and is connectable to a vehicle structure, a reinforcing element composed of fiber-reinforced plastic, where the reinforcing element is accommodated in the side sill, and at least one flat connecting surface which connects the outer wall element to the inner wall element and is oriented substantially parallel to the XY plane of the vehicle.
The use of fiber-reinforced plastic, in particular carbon-fiber-reinforced plastic (CFRP), ensures a low weight of the impact protection element according to the invention. The advantage here is that a CFRP part which can absorb just as much energy as a metal part weighs only approximately one half to one third. The vehicle thus becomes lighter in weight and consumes less fuel.
Furthermore, it is ensured by the substantially parallel alignment of the reinforcing element with the XY plane of the vehicle that the flat connecting surface is oriented substantially orthogonally to the crash test pole or a tree/post which extends parallel to the Z direction of the vehicle. Energy is then absorbed by destruction of the flat connecting surface. This alignment is particularly advantageous in order to absorb energy. Furthermore, the pole/tree/post, etc., always strikes substantially orthogonally against the flat connecting surface, and therefore the advantageous energy absorption behavior of the reinforcing element is always ensured. The intrusion is significantly reduced as a result. While known impact protection elements composed of metals have an intrusion of 250-350 mm under test conditions, an impact protection element according to the invention can have an intrusion of just 150-250 mm.
Furthermore, the connecting surface aligned according to the invention increases the rigidity of the side sill. Other loads apart from the crash loads can therefore also be supported. In summary, an integration of components and an integration of functions are therefore ensured.
In a preferred embodiment, the reinforcing element extends substantially over the length of the side sill. The side sill thereby provides the particularly advantageous energy absorption behavior over its entire length.
According to a further embodiment, the reinforcing element is formed integrally with the outer wall element or the inner wall element. The outer wall element can be formed integrally here with the connecting surface, the inner wall element can be formed integrally with the connecting surface, or the outer and inner wall element can be formed integrally with the connecting surface. The integral construction enables the impact protection element according to the invention to be produced cost-effectively. For example, a pultrusion method for producing the impact protection element is preferred.
According to another embodiment, the reinforcing element and the side sill are formed separately. In this case, the reinforcing element is attached to the outer wall element and to the inner wall element and connects the wall elements to each other in this manner. This modular or differential construction permits greater flexibility in production. For example, the same side sills can be provided with different reinforcing elements which meet different requirements.
In a particularly preferred embodiment, the outer wall element and the inner wall element are formed separately here and include flanges for connecting the inner wall element and the outer wall element. The flexibility in production can thereby be further increased. For example, the same outer wall element can be connected to different inner wall elements which are connectable to different vehicle structures.
In one embodiment, the reinforcing element is designed as a hat profile which includes two flat connecting surfaces, an outer planar attachment element and two inner attachment surfaces. By means of the planar attachment of the reinforcing element on the side sill, the rigidity of the latter is increased further. Furthermore, the energy absorption is increased by the two flat connecting surfaces.
In this embodiment, it is advantageous that the reinforcing element is formed integrally. The reinforcing element can thereby be provided in a simple and cost-effective manner.
However, it is also advantageous that the first connecting surface, a first outer attachment surface and the first inner attachment surface are formed integrally; and the second connecting surface, a second outer attachment surface and the second inner attachment surface are formed integrally. The first outer attachment surface is connected here to the second outer attachment surface in an overlapping manner in order to form the outer planar attachment element. The flexibility in production can thereby be further increased.
In another embodiment, the reinforcing element is designed as a box profile which includes two flat connecting surfaces, an outer planar attachment element and an inner planar attachment element. By means of the planar attachment of the reinforcing element on the side sill, the rigidity of the latter is increased further. Furthermore, the energy absorption is increased by the two flat connecting surfaces.
In a preferred embodiment, the impact protection element furthermore includes a honeycomb structure composed of a fiber-reinforced plastic, which honeycomb structure is accommodated in the side cell, in particular in a cavity formed by the reinforcing profile. The energy absorption can thereby be further increased.
The invention also includes a vehicle with an impact protection element according to the invention.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.